


Trapped

by Anonymous



Category: Supernatural
Genre: BAMF Castiel (Supernatural), Castiel & Sam Winchester Friendship, Castiel To The Rescue, Crying Sam Winchester, Drowning, Gen, Hurt Castiel, Hurt Sam Winchester, Kidnapped Sam Winchester, Underwater, merman Sam, suffocation
Language: English
Status: Completed
Published: 2018-11-10
Updated: 2018-11-10
Packaged: 2019-08-21 10:00:47
Rating: Teen And Up Audiences
Warnings: Graphic Depictions Of Violence
Chapters: 1
Words: 4,263
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/16574342
Author URL: https://archiveofourown.org/
Summary: The search for Dean leads Sam into danger when he is kidnapped and changed.But Castiel knows something is wrong. He will find Sam, and nothing better get in his way.





	Trapped

It was just after noon when Castiel arrived at the diner. He didn't see the Impala in the car park; he went inside and took a booth from where he had a good view of the cars coming and going, and the door, and ordered some coffee. 

After ten minutes, he ordered a sandwich, knowing he'd only draw attention, and possibly be asked to leave, if he didn't actually purchase something. 

The food went uneaten. Cas watched people come in on their lunch break; some sat down to eat, and some took paper carry out bags away with them. 

People passing through came and went, Cas eavesdropping on their conversations and their thoughts, just in case. Lately it seemed they couldn't trust anybody, and Sam has made him promise: from now on, they put their family first. 

Losing Dean had changed Sam. Cas could see it, but then it had changed him too he supposed. 

He glanced at the clock on the back wall. Sam had said noon. It was now half past one and there was no sign of him. 

Cas took out his phone but there were no texts either. 

He sat there, wondering if Sam were simply occupied or if something had happened. It might be he was simply delayed. 

It might not. 

Cas stood up, leaving some money on the table, and went out to his truck. He looked up the GPS for Sam's phone, and put his own in the cradle on the dash so he could follow the map. 

Sam's phone was still in Bellington, where he'd gone to speak to a witch that might be able to help them since Rowena was still picking and choosing when to get involved with their current fight. 

Cas rang Sam's phone as he pulled out of the car park, but got no response. In truth, he hadn't been expecting one. 

Sam hadn't prayed to him, but all the same, Cas was sure something was terribly wrong. 

++

“Fuck,” a voice said. “Son of a bitch is heavy.”

Sam groaned as pain brought him slowly to consciousness. He felt groggy, and sick. Whoever was carrying him was no good at it; his weight seemed to be throwing them off, making them haul him awkwardly, so it wasn't Cas.

Cas could have lifted him easily, and wouldn't be half dragging his ass along the ground. 

“Yeah,” someone else said. “What the fuck do you expect? Dude was huge before; now look at him!”

Sam forced his eyes open. What did they mean? Two of them had an arm each, using them to keep his upper body mostly off the ground. Sam's head lolled between them, but he ignored the awful pain in his neck and forced himself to look around him. 

He didn't recognise the men carrying him, or what he could see of his surroundings...some kind of dirt road running through the trees. 

But then he saw why the men carrying him were having so much trouble and his head cleared in an instant. He remembered the town and the old bar where someone had given him directions to the ramshackle house on the cliff. 

He remembered the witch and feeling off the minute she'd invited him in. But desperation had trumped caution and by the time he was sure she meant him harm, he was already nauseous and in pain. 

_Never trust a sea witch_ , she'd told him. 

The last thing Sam remembered of that house was her on the phone, telling someone to come get him, and not to forget the cash. 

No. That wasn't the last thing he remembered. The last thing he remembered was the same thing he was looking at now. 

A tail. 

His tail, where his legs used to be. At least two thirds the length of his body, with fins and scales that had an iridescent sheen to them. 

It was taking four of them to carry that part of him, and they were red faced and panting with the effort. 

One of them noticed him staring then, and cried out, “Hey, he’s awake!”

Sam grabbed the wrist of the man on his right, yanked it to his mouth and bit. 

Apparently his teeth had changed too; the skin and flesh parted instantly and he gagged on the hot copper taste that filled his mouth. 

That man screamed and beat at his head until Sam let go. The others dropped him, knocking the wind from him, but he wasn't about to surrender. He punched the knee of the guy closest to him, felt a grim relief as he went down yelping. 

But that left four, and Sam wasn't sure how he could beat them lying on the ground with nearly five and a half feet of fish tail. 

One way to find out. Moving the tail hurt but it was a hundred pounds plus of pure muscle and Sam needed every advantage. 

His first tail attack was glancing and flimsy. He barely managed to nudge one of them back. 

The second attempt though was much more successful; Sam knocked one of them off his feet and that just left three. 

And that was when his luck ran out. 

One of them had some kind of cloth. He tore it in pieces and then his friends started to move around Sam, circling him, looking for an opening. 

Sam’s arms throbbed with the effort of keeping his upper body off the ground. One of them launched a kick at his elbow and that arm collapsed beneath him, dumping him on his back, and they were on him. 

Two of them pinned his arms and the third grabbed hold of the cloths, now ragged and torn. He put his hand on Sam's side and Sam looked down and _holy shit_. 

He had gills. 

And then his side was on fire. 

The man was stuffing some of the rags in between the slits, fingers tamping the material down, and Sam jerked and fought, head turning woolly with the pain. 

When the man did the same on his other side, he felt his breath hitch with panic. 

Then the man straddled him and held up the last piece of cloth. 

“You’re half and half like this,” he told Sam. “You can breathe fine through air and water. But not if you’ve got something stuffed in every damn airway, do you get me?”

Sam eyed the cloth. It already felt like he was getting less air but that might be the pain. The panic. 

He couldn't risk it. Since that cabin…. He’d never told Dean about the nightmares but he couldn't go through that again. 

Sam nodded once, glaring at the man threatening him. He seemed satisfied, and got up. He roused the ones Sam had knocked down, and they picked him up again, less gently than before, and hauled him to an flatbed truck. 

He ended up stuck in the back, covered with an oily tarpaulin, hands tied to where his hips would have been, the rope biting into his skin and flaking off scales. 

They left the cloths stuffed deep in his gills, and eventually, exhausted and weak, Sam passed out. 

++

He woke up, shivering, and found he was no longer in the truck. Blinking drowsily, Sam tried to push himself upright, but then a foot connected with his shoulder and pushed and then he was falling. 

Not far, though; water broke his fall, cold, and startling the last of the mugginess from his head. 

Sam managed to right himself but his tail was heavy enough that it was like wearing lead weights; he tried to stroke upwards, but without knowing how to propel himself with his new appendage, he was stuck on the bottom of what appeared to be some kind of glass tank. 

He panicked until he realised he wasn’t drowning. He did feel lightheaded but he was getting air. Just not enough. 

The rags were still stuffed in his gills. As he tugged at them, he heard a muted grating sound from above. 

Looking up, he could see the men who had brought him here. They were heaving a metal cover into place over the tank entrance. 

Sam screamed at them, his voice garbled by the water, but they kept going. The lid slammed into place, and they fiddled with it a little more before moving away. 

They were back a few moments later, though; appearing from the side of the tank and coming around the front to grin and mock and rap their knuckles at him. 

Sam didn’t know what they were saying, but his temper seethed. He rocked back and his tail seemed to take on a life of its own, snapping forward to smash against the glass. 

They jumped back and that moment of fear in their eyes was worth the sharp throb in his tail from the impact. 

But the glass held. 

One of the men drew his forefinger sharply across his own throat before they turned and went, leaving him alone. 

Sam shut his eyes, hoping Cas ‘had his ears on’ as Dean liked to say. 

_Cas, buddy; I hope you can hear me cos I really need you right now._

++

The house was old; to Cas, it looked like the merest gust of wind would send it rolling over the edge of the cliff and down to smash on the rocks below. 

But Sam was here, or at least his phone was. 

Cas got out of his truck and tried to quiet the unease he’d felt since Sam had missed their rendezvous. It didn’t mean he was in trouble, the angel told himself. There could be any number of reasons, also, why he wasn’t answering his phone. 

And Sam still hadn’t prayed to him for help; even if he was somehow unable to call, angel radio was always a sure fire way of reaching him. 

All the same, Cas’s fears wouldn’t be dismissed. Only when he could see with his own eyes that Sam was alright, would he be able to settle. 

He went up to the door, and knocked. After a moment, it opened, and an elderly woman glanced questioningly at him. 

Cas could feel the magic in her, so knew he’d found the witch Sam had come to see. 

“I’m looking for my friend,” he said and described Sam to her. 

She shrugged before he’d finished. “No one’s been by here in a couple of days. And no one like you’ve described.”

On reduced Grace, he lacked the angelic ability to probe deep enough and sense if she was lying, but the fact that Sam’s phone was here proved it. 

The question was what to do about it. 

“Maybe he’s delayed,” Cas went on. “I was going to meet him here. We need your help.”

She shook her head. “I don’t have any money if you’re begging or collecting for charity.”

“A different kind of help. I can pay.”

The witch’s expression changed. “Come in. Tell me what you need.”

She stepped back, motioning for Cas to precede her. He did, heard her close the door, and then follow him. The house had a nasty smell to it; Cas could easily imagine himself in a sea cave, dark and damp. He could almost hear waves lapping. 

And then he heard her hiss at him, low and hateful, and he turned in time to see an eerily glowing vapour exuding from her mouth as her eyes burned with magic. 

Cas stepped through the miasmic fog unharmed and grabbed her by the throat. 

“I will personally deliver you to Hell,” he said. “I’m on first name terms with the King.” Or had been. 

The vapour faded, and the witch clawed at his hand.

“What...what…”

Cas shook her, hard. Telling her his true nature might give her a way to attack him. “Where’s Sam?”

He saw her expression turn wily for a brief moment, and increased the pressure in his grip. “Don’t test me.”

“How do I know you’ll let me live if I tell you,” she croaked. 

Cas yanked her forward, on to her tiptoes. “Right now you should be more concerned about what will happen if you don’t. Now what did you do?”

He could see when she decided to co-operate, at least temporarily. She sagged, and Cas loosened his grip but only enough for her to speak freely. 

“What they pay me to. It’s nothing personal.”

Cas glared at her. “Wrong.”

++

It took Sam a while to finish freeing his gills ( _his fucking gills_ ) completely. By the time he was done, digging out the last tangled threads, they felt raw but it was a lot easier to breathe. 

Now...now he has had to figure out what to do next. 

It didn’t seem like he had a whole lot of options. 

His tail was still a stubborn anchor (unresponsive since the earlier shows of temper and defiance), keeping him weighted to the bottom of his glass prison. 

It wasn’t huge either; a few metres either way (probably just a couple of flicks of his powerful tail) and he’d have to turn around. 

But even if he could swim, and he could reach the large metal hatch sealing him in, and he could get it open, well…. What then?

It wasn’t like he could climb out and run away. 

Without help, he was stuck in here and he didn’t know the how or the why. 

Dean would never let him live this down, not once he was safe and wholly human again. Sam knew he’d be finding fish flakes in his meals for at least a year, and getting them wrapped for his birthday and Christmas. 

Fuck. He never thought he’d miss what an asshole Dean could be sometimes. 

Sam clenched his fists and glared at his tail. This was his problem right now, and he used it to block out the aching loss. 

Cas would find him. Somehow. 

Someone caught his attention then and Sam watched warily as some people gathered to stare at him. 

They were all pointing and talking and he wondered if this was what animals in aquariums felt like and pet fish in tanks. Why they had castles and rock piles, to hide from stupid gaping humans. 

Sam didn’t have any cover at all, and even if he had, he wouldn’t have been able to reach it. 

So he brazened it out and glared back and eventually the people went away. 

Sam then went back to glaring at his tail. 

His own body, fucking sabotaging him _again_. 

++

Cas has used his Grace to fetter the witch’s magic but he could feel her prodding at it, picking away, probably imagining him unawares. 

He worried that if she continued, she might find a weak spot, a threadbare patch, and so he swatted her tendrils of dark magic away hard. 

She gasped and when he glanced sideways at her, blood was trickling from her nose. 

He had no sympathy. 

She was silent now, as he drove the rest of the way to the bar, but she had told him grudgingly what she had done. And not just to Sam, though he was her most recent victim. 

He was horrified, and wondered if Sam’s current form was why Cas couldn’t hear his prayers, because he would be praying, Cas was sure. 

Frantic and scared. 

But hopefully still alive and unaware of what they had planned for him. 

The witch said the time the men at the bar kept their captives varied. It really depended on the appetites of their clientele. 

Some people had very exotic tastes. 

Cas drove faster at the thought of it. If he was too late…

No. He wouldn’t be. 

But if he was…

If he had lost Sam, Cas would show all of them the wrath of Heaven.

And of Winchesters. 

++

By the time they arrived, it was dusk. Cas parked behind a side panel van that kept them out of view of the door, and then got out. 

He hauled the witch after, ignoring her protests. Leaving her at the house hadn’t been an option; she might have warned the people who had Sam. 

And besides, Cas knew he would need her to reverse the spell. It was likely also that she knew the layout of the bar and where they were keeping Sam, creating more reasons for Cas to keep her close. 

And alive. 

He’d made it clear though that if she betrayed him or they didn’t recover Sam, she shouldn’t expect his mercy. 

Now, with her in hand, Cas went around the van and then down the side of the building. There were only a couple of other cars, but around the back, Cas found what he guessed was the staff car park. 

And there was the Impala, bearing out what the witch had told him: that while the rest of the men hauled Sam away, one more drove the car. 

Cas imagined they would have sold her, eventually, like they probably had with the other victims’ vehicles. 

Not this time, though. 

There was a staff entrance further on, and a man in dirty kitchen whites standing there, smoking. 

He didn’t hear them, and then Cas tapped two fingers to his forehead and caught him one handed as he fell, lowering him quietly to the ground. 

He’d be found soon enough, but this wouldn’t take long. 

The kitchen was otherwise deserted; the witch had told him this was a small operation and that made sense. The fewer people involved, the less chance of the wrong people finding out what they were up to. 

Cas pulled the witch behind him, through the kitchen, past an open storage area, and then down a dingy corridor. 

“He’ll be through there,” she whispered. “Looking different from when you last saw him.”

Cas squeezed her arm. “But not for long.”

She nodded, eager now to keep on his good side. 

Cas still wasn’t about to trust her, and kept a tight grip on her arm as they rounded a corner and there Sam was.

Despite knowing what the witch had done, Cas was still stunned to the spot. Sam didn’t notice them at first. He was struggling, trying to haul himself along the bottom of a giant water filled tank, but his huge tail had him trapped, held back, and Cas could see his frustration building until he turned and slammed a punch into the glass. 

That was when he saw them and Cas could tell Sam was screaming his name. 

A moment later something sharp plunged like fire into his back. 

++

Cas, Cas was here! And he had the sea-witch with him, but Sam’s relief was over too fast. 

He tried to scream a warning, but the man behind Cas stabbed him anyway and Cas went down to his knees. 

Sam slammed his fists against the glass; he couldn’t get out, but even if the only help he could give Cas was distraction it was better than nothing. 

But then Cas stood up, and turned. His back was bloody and Sam yelled again, wishing he could drag that bastard into the tank with him, because a mortal weapon still might not be able to kill Cas, but the days of him shrugging off the damage were long gone. 

It didn’t stop him back handing the guy, sending him flying into the wall and coming down with his neck at an angle that told Sam he wouldn’t be getting up again. 

The other guys came crawling from the woodwork then, launching themselves at Cas; Sam saw the glint of the angel’s blade as he dispatched two of them, but a third had a gun and he fired in panic. 

Sam guessed they weren’t used to their victims being able to fight back. 

Two things happened then. One of the bullets winged Cas, staggering him. 

The other hit the witch who just hadn’t been quick enough to get clear when the melee started. Or maybe he meant to hit her; she betrayed them after all, leading Cas here. 

Intended or not, it took her in the throat, a through and through, and she was dead before she hit the ground. 

Either way, like cause and effect, Sam felt a painful tug inside himself, like his body was rearranging itself. 

_Fuck_ ,

It took seconds and then Sam was screaming. His tail tore in two and then he has legs again; his ribs cracked and reset themselves and then his gills were closing over. 

The pain got bad enough that he wasn’t sure it wouldn’t kill him. 

But then it was over, and he was human again. 

Which immediately presented Sam with another problem. 

He was human again and trapped in a tank full of water, with no way out. 

++

Cas grabbed the gun, and broke the man’s wrist as he wrenched it away. As the man screamed, Cas drove his elbow into the man’s throat and he collapsed, gagging to the ground.

The angel stared at the dead witch, her face and torso streaked with blood. Spells usually died with the caster, so…

Sam!

Cas ran to the tank. Sam was desperately thumping on the glass, pointing up to where Cas guessed the hatch to the tank was. 

That would take too long. 

Cas put his hand on the glass and summoned his Grace, sending a pulse out to make it tremble. 

A spiderweb of cracks spread across the surface and a moment later the whole sheet gave way. 

Gallons of water thundered out at him, bearing Sam down on him as well. 

Cas caught hold of the hunter, and wrapped himself around Sam as much as he could. The torrent carried them across the room, slamming them into the wall, but Cas took the impact and then got them both onto their knees. 

“Sam! Sam, are you alright?”

He was cold and wet and coughing helplessly, so Cas cupped his face and sent Grace rippling through him, healing whatever injuries he had. 

Sam was also naked and that Cas had to deal with by more normal means. He took off his coat, and wrapped it around Sam, aware it was too small and too thin to do much good but better than nothing. 

Sam sagged against him, and Cas hugged him tightly. “I’ve got you,” he said. 

He helped Sam to his feet and then stared at the floor: wet and strewn with glass. 

Sam couldn’t walk on that. He lifted him easily, expecting protests but Sam seemed to get it, and held on. 

Cas didn’t know why he felt so comforted by that; maybe it was just knowing Sam was safe, but he held him a little tighter as he bore him outside. 

++

Sam got changed in the back of the Impala, Cas standing guard. Then, at his insistence, he’d made Cas let him check his wounds (the knife wound first but that had already to close over; Sam had dug out the bullet from the gunshot wound, and dressed both just in case).

Then Sam followed Cas’s truck until they pulled in at a motel several towns over, where Cas booked them a room. 

Inside, Sam collapsed gratefully onto the first bed. “They were going to _eat  
_ me?”

He shuddered. 

Cas sat down opposite him. “Eventually. The witch said this had been their bread and butter for years, catering to a select ‘clientele’.”

Sam thought back to when he’d been sympathising with pet fish. 

Instead, it should have been lobsters. 

“Sending people to the witch so she could turn them?” Or was it just the people like him who’d went looking for trouble?

Cas seemed to read his self-incrimination, or maybe he could sense what Sam was feeling now he was human again. He’d explained how he’d tracked Sam down, unable to hear his prayers. 

“Or sometimes, if they caught a lone traveller or even a family who wouldn’t be missed and could be ‘disappeared’ easily enough, they’d take them or have her come to them. 

“But they didn’t always need her services. There used to be a community of merfolk in the nearby waters.”

Used to be. Sam had a feeling he didn’t want to know, but it felt like he had to. He gave Cas a questioning look. 

“They got greedy,” Cas said. “Pollution and climate change did the rest, though it’s possible some of them just moved on.”

Sam smiled at Cas’s obvious, but still welcome, attempt at comforting him. He didn’t have to; having Cas there, close, was comfort enough. 

“Cas, I…. Thanks, Cas. For getting me out of there.”

Cas smiled. It was a rare occurrence these days. He chided himself for the dishonesty; seeing Cas smile had always been rare, and he felt a sharp stab of guilt at that. Once they got Dean back, though, that’d change, and…

He didn’t know where the tears came from but suddenly he was shaking and bawling and for the second time that night, an angel took him in his arms. 

And held him there, telling him they’d fix this, get Dean back, and that Cas would always, _always_ come for him. 

Sam must have cried himself to sleep, it and exhaustion combining to knock him out, and Cas must have got him undressed and under the blankets, because he woke in the morning feeling warm and safe and kind of wrung out. 

And Cas was hanging up on someone. He saw Sam was awake and came over. 

“That was Mary,” he said. “We have a lead on Dean.”


End file.
